The major goal of this proposal is to investigate biomarkers of lung cancer risk in a population with occupational exposure to asbestos, a known pulmonary carcinogen. Sputum cytology and urinary bombesin-like peptide (BLP) levels are the biomarker outcome variables. We have completed data collection on 220 study participants meeting eligibility criteria of age > 40 years and at least 15 years of asbestos exposure. We have found high prevalence rates of radiographic asbestos-related diseases (16% asbestosis and 31% pleural abnormalities); high rates of airflow limitation (51% with FEV1 < 70% predicted); and high rates of sputum cellular atypia (28% moderate atypia, 49% mild atypia, 4% squamous metaplasia, 19% normal, and 10% unsatisfactory specimens). These data demonstrate our ability to recruit individuals at high risk for lung cancer, show that sputum cytologic abnormalities are frequent in asbestos-exposed construction trades workers, and lay the foundation for a chemoprevention trial.